Cup topping machine



Dec. 5, 1967 Filed Jan, 13, 1965 IS@- W C5` EEONNING CUP TOPPING MACHINE2 Sheets-Sheet 1 fvzzw *s INVENTOR.

Dec. 5, 1967 N. G. EONNING 3,355,840

CUP TOPPING MACHINE Filed Jan. l5, 1965 2 Sheets-Sheet 2 IN VEN TOR.

M5490/ 6'. BOA/L//A/G United States Patent O 3,355,840 CUP TOPPINGMACHINE Nelson G. Bonnng, Warren, Pa., assigner to Buffalo China, Inc.,Buffalo, N.Y., a corporation of New York Filed Jan. 13, 1965, Ser. No.425,202 16 Claims. (Cl. 51-71) ABSTRACT F THE DISCLDSURE A toppingmachine providing a chum to support a piece of hollowware with its rimin engagement with a rotating abrasive disc. Power means operate toprogressively deform the abrasive disc while it contacts the rim from afirst position in which the disc is substantially normal to the rim to asecond position in which the disc extends generally axially around therim. The progressive deformation causes the disc to progressively roundoff the rim. Springs urge the chum away from the disc with a force whichis substantially constant while the topping operation progresses.

This invention relates generally to machines for the production ofhollowware and more particularly to a topping machine for smoothlyiinishing the rim of a piece of hollowware, such as a ceramic cup or thelike.

Many types of hollowware formed of ceramic material and other types ofmaterials are formed by molding. When the piece of hollowware is removedfrom the mold a sharp and rough surface is usually present along theexterior surface of the rim of the piece. This rough and irregularsurface results from the joint between the separable mold members usedto form the piece.

Various methods have been utilized in the past to eliminate this roughand sharp edge so that the rim surface smoothly blends into the adjacentsurfaces. One commonly used method of rounding and smoothing the rim hasbeen to place the piece of hollowware upright on a rotating rubber churnand touching the rim with a carboloy tool ground to shape the rim. Withsuch a method considerable operator skill is required if the operationis to be carried out rapidly since the tool must be precisely positionedto form the smooth surface without damaging the rim. Experience hasestablished that skilled operators can top approximately eighty-livedozen cups per hour by this prior method of operation.

-With a topping machine incorporating this invention essentially noskill is required and uniformly high quality articles are produced. Inpractice it has been found that unskilled labor using a machineaccording to this invention can top in excess of ninety-tive dozen cupsper hour and that the quality of the surface of the rim produced isuniformly as high or better than the surfaces produced by other highproduction topping procedures and apparatus.

It is an important object of this invention to provide a novel andimproved topping machine for hollowware which eliminates the necessityof operator skill while producing uniformly good quality rim surfaces athigh production rates.

It is another object of this invention to provide a novel and improvedtopping machine for ceramic hollowware which includes a member having anabrasive surface and power means to produce relative movement betweenthe rim of the piece of hollowware and the abrasive surface whileautomatically shaping the surface to smoothly blend and round the rim ofthe hollowware.

It is still another object of this invention to provide a novel andimproved topping machine for hollowware including a churn forpositioning the hollowware in the machine and power operated meansautomatically oper- 33,355,84@ Patented ec. 5, 1967 ICC novel andimproved topping machine for hollowware including a deformable abrasivemember engageable with the rim of a piece of hollowware positioned inthe machine and automatic power operated means to produce relativemovement between the piece of hollowware and abrasive surface whiledeforming the abrasive surface up around the edge of the hollowware toform a smoothly blended rim.

lt is still another object of this invention to provide a novel andimproved topping machine for ceramic hollowware including a chum tosupport a piece of hollowware, a disc of abrasive material containingsubstantial openings to prevent clogging, a chuck to support the discfor rotation, a deformable rubber-like backing member and means todeform the backing member and abrasive disc from a first position inwhich the surface of the disc is generally along a plane to a secondposition in which the surface of the disc is deformed to a generally cupshape so thatthe rim of the piece of hollowware will be rounded andsmooth.

Further objects and advantages will appear from the followingdescription and drawings wherein:

FlGURE l is a side elevation partially in longitudinal sectionillustrating the structural detail of one preferred embodiment of cuptopping machine incorporating this invention with the elements in theposition they assume immediately after the cup is positioned in themachine and prior to the cup topping operation;

FIGURE 2 is a fragmentary view illustrating the position of the elementsat the moment the topping operation commences;

FIGURE 3 is a fragmentary view illustrating the position of the elementsat the completion of the topping operation; and,

FIGURE 4 is a fragmentary view illustrating the cup topping machinemodied for smaller diameter cups.

A. topping machine incorporating this invention is illustrated in thedrawings in the operations of topping a ceramic cup. It should beunderstood, however, that this invention is applicable to the topping ofother forms of ceramic ware and also the topping of articles formed ofmaterials other than ceramic materials, such as for example certaintypes of plastic and the like. The -v cup illustrated is sufficientlydry to have a reasonable degree of strength but is topped before eitherfiring or glazing. The cup is formed by molding or any other suitableprocess and requires topping to produce a. smooth, rounded rim surface.

The illustrated topping machine is mounted on a base 10 provided with atable-like upper surface f1. Legs 12 rest on the Hoor and support boththe upper surface 11 and a lower surface 13. A bearing sleeve 14projects through the upper surface 1l and is welded in place to providea rigid support.

A rotating chuck 16 is provided with a tubular extension 1'7 extendingthrough the bearing sleeve 14 and supported for rotation therein onspaced anti-friction bearings 18 and 19. The lbearing sleeve t4 isprovided with opposed shoulders 21 and 22 which axially support thebearings 13 and 19 respectively. Radial support is provided by a closelit between the respective bearings and cylindrical surfaces 23terminating at the shoulders- 21 and 22,. The inner race of the bearing18 is seated against a shoulder 24 formed on the rotating chuck 16adjacent to the end of the tubular extension 17. A ring 26 is threadedonto the lower end of the extension 17 and engages the inner race of thebearing 19 urging it upwardly toward the shoulder 24. This causes therespective outer races to tightly engage the shoulders 21 and 22 andaxially locates the rotating chuck 16 on the base 10 for rotation abouta central axis 25. A jam nut 27 is tightened against the ring 26 whenthe ring is properly adjusted to prevent relative rotation between aring 26 and tubular extension 17. A pulley 28 is mounted on the ring 26by bolts 29 and is connected by a V-belt 31 to an electric motor whichrotates the chuck 16. The electric motor has not been shown in order tosimplify the illustration, however, it is supported on the base in aconventional manner.

The rotating -chuck 16 is formed with a circular base 32 and anupstanding cylindrical flange 33. A wooden chuck 34 is sized to fitwithin the flange 33 against the base 32 and is locked in position bybolts 36 extending through threaded apertures in the flange 33. Thewooden chuck is formed with an annular recess 37 and a central aperture38. The recess and aperture cooperate to form a guide stem 39 and anupwardly extending cylindrical flange 41 having a rounded corner 42which forms an annular support surface. A foam rubber disc 43 having adiameter sufficiently large so that it extends radially beyond thecorner 42 and a centralopening 44 proportioned to closely fit the guidestem 39 acts as a backup for a disc of abrasive 46. The engagementbetween the guide stern 39 and the central opening 44 radially locatesthe rubber disc 43 and cooperates with the engagement between the corner42 and rubber disc to cause the disc to rotate with the chuck 16.

The abrasive disc 46 is formed of a material which is normally fiat butis deformable to a generally cup shape and which is capable ofabrasively smoothing the rim of a ceramic cup 47 in the leather hardstate. The abrasive disc is formed of a material that will not becomeclogged in use and will not wear rapidly. One material which has beenfound in practice to operate very satisfactorily is a material formed ofa mass of loose deformable fibers supporting spaced abrasive particles.One such material is more completely described in the United StatesPatent to Hoover et al., No. 2,958,593, dated Nov. l, 1960.

The abrasive material 46 is mounted on an axially movable actuatingassembly 48. This assembly includes a hollow shaft 49 extending upthrough the tubular extension 17 to an end surface 51. A lock nut 52 isformed with a threaded stem 56 which is threaded into the upper end ofthe shaft 49. A shoulder 53 on the lock nut 52 engages the inner race ofa bearing 54 and firmly presses it against the end surface 51 of theshaft to axially support the bearing 54 on the shaft. A cylindricalsurface on the stem 56 closely fits the inner surface of the inner raceto radially locate the bearing. A radial skirt 57 on the lock nut 52covers the bearing 54 and limits entry of dirt or other foreign matter.

A mounting ring 58 for the abrasive disc 46 closely ts the outer race ofthe bearing S4 and is threaded to receive mounting bolts 59 whichperform the dual function of securing the mounting ring 58 to the outerrace and clamping the abrasive disc 46 between two plates 61 whichengage opposite sides of the abrasive disc 46. The upper `plate 61cooperates with a shoulder 62 to lock the mounting ring 53 to the outerrace o-f the bearing 54.

With this structure the central portion of the abrasive disc 46 isradially and axially located with respect to the chuck assembly 48 butis free to rotate relative thereto under the influence of its engagementwith the rubber disc 43. When the elements are in the positionillustrated in FIGURE l the abrasive disc 46 extends generally radiallywith respect to the central axis. However, when the actuating assembly48 is pulled downwardly with respect to the wooden chuck 34 to theposition illustrated in FIG- 4 URE 3 both the rubber disc 43 and theabrasive disc 46 are deformed to a generally cup shape symmetrical aboutthe central axis 25 of the machine so that portions of the abrasive disc46 extend more nearly parallel to the central axis of the machine.

During the topping operation the cup 47 is supported on a rubber chum 63proportioned to closely fit the inner surface of the cup 47 leaving itsrim 64 exposed. The rub-ber chum 63 is threaded onto the upper end of arod 66 which extends down through the lock nut 52 and is laterallysupported thereby. The lower end of the rod 66 extends through a bearingnut 67 threaded onto the lower end of the shaft 49 and is provided witha stop nut 76 engageable with an adjustable stop 68 mounted on the lowersurface 13.

A ring 69 is axially fixed on the rod 66 by a set screw 71 and isconnected by tension spring 72 to a spring support ring 73 secured tothe shaft 49 by a set screw 74. The springs 72 produce a resilient forceurging the rod 66 and in turn the churn 63 upwardly with respect to theshaft 49 and the value of this force is adjustable by adjusting theposition of the spring support ring 73 along the shaft 49. Therefore,the chum 63 is normally in an upper position, as illustrated in FIGUREl, but is movable against the action of the springs 72 downwardly to thepositions of either FIGURE 2 or FIGURE 3. The maximum downmovementoccurs when the stop nut 67 engages the adjustable stop 68 and is theposition illustrated in FIGURE 3.

In order to provide axial movement of the shaft 49 an air cylinder 76 ismounted on the lower surface 13 and is provided with a piston 77engageable with an adjustable stop '78 threaded into an actuating arm79. The arm 79 is formed with a bore 81 through which the shaft 49extends. A clarnping bolt 82 is tightened to lock the arm on the shaft49. Opposed vertically extending stops 83 (only one of which isillustrated) are mounted on the base 10 and positioned to engage the arm79 and prevent rotation of the shaft 49 with the rotating chuck 16. Aspring 84 connected between the end of the arm 79 and a support 86 urgesthe shaft 49 in a downward direction with a force which is determined bythe adjustment of a screw 87 threaded into the support 86.

When air pressure is supplied to the cylinder 76 the piston 77 extendsraising the shaft 49 to the position illustrated in FIGURES 1 and 2.However, when the cylinder 76 is exhausted to atmosphere the spring 74produces sufficient force to lower the shaft 49 until the lower plate 61engages the upper end of the guide stern 39, as illustrated in FIGURE 3.

The cylinder 76 is connected to a source of air pressure, such as a pump88 through a normally open solenoid valve 89 and a pressure line 91.When the valve 89 is not energized the pump 88 is connected through theline 91 and the cylinder 76 is pressurized causing the piston 71 toextend to the position illustrated in FIGURE l. When the valve 89 isenergized it connects the pressure line 91 to atmosphere, exhausting thecylinder 76 and allowing the piston 77 to retract under the influence ofthe force of the spring 84. The rate of retraction of the piston 77 canbe controlled by an orifice type fiow restriction (not shown) mountedeither in the connection between the pressure line 91 and the cylinder76 or in the exhaust of the solenoid valve 89. Generally, however, thefriction in the line 91 and adjustment of the spring 84 is used toobtain the desired rate of movement.

To operate the solenoid valve 89 a microswitch 92 is mounted by a screw93 on the lower surface 13 and is provided with an operating arm 94engageable by the lring 69. The arm 94 is formed of spring metal topermit overtravel. The microswitch 92 is of the normally open typeconnected through a pair of electrical conductors 96 tothe solenoidvalve 89 and in turn to a supply line 97 conneeted to a suitable sourceof electrical power.

In a topping operation a cup 47 is placed on the chum 63, as illustratedin FIGURE 1, the operator then presses downward on the cup causing thechum 63 and the rod 66 to move downwardly. This causes the ring 69 toclose the switch 92 when the cup reaches the position of FIGURE 2. Atthis time the rim 64 of the cup 47 engages the abrasive disc 46 which isrotating with the rotating chuck 16. Since the microswitch closes atthis instant the axially movable chuck assembly d8 is still in the upperposition and the abrasive disc 46 engages the rim 64 of the cupsubstantially perpendicular to the central axis of the cup, asillustrated in FIGURE 2. However, the operation of the switch 92 causesthe cylinder 76 to be exhausted and the actuation assembly 43 commencesto move downward to the position of FIGURE 3. During such movement theoperator maintains downward pressure on the cup 47 so the rim 64 of thecup remains in engagement with the abrasive disc 46 While the disc isbeing deformed to the cup shape, illustrated in FIGURE 3. All of thisoccurs while the disc 46 rotates relative to the rim of the cup 47 sothe outer surface of the rim 64 is rounded and smoothed completing thetopping operation.

Because the spring support rings 73 move downward during the downwardmovement of the shaft 49 the upward force produced by the spring 72during this operation of topping actually reduces slightly. Therefore,the operator does not have to increase the pressure during the toppingoperation but merely maintains the pressure necessary to cause downwardmovement of the ring 69 and closing of the switch 92.. In effect, themachine operator merely presses down on the cup with a uniform forceduring the entire topping operation, so operator skill is eliminated. Assoon as the stop nut 67 engages the adjustable stop 68 the operatorrealizes that the topping operation is completed since the cup does notcontinue to move downward. The operator is therefore informedautomatically that the topping operation is completed and he merelyreleases the downward pressure and the springs 72 raise the cup back tothe position of FIGURE i. This permits the switch 92 to close and thecylinder 76 is again pressurized to raise the axially movable chuck 48back to the position of FIGURE 1 ready for the next cycleV of operation.The operator then removes the cup which has been topped and places thesubsequent cup on the churn and repeats the cycle of operation.

When it is desired to top cups having a smaller diameter a series offoam rubber rings 98 may be placed within the wooden chuck 34, asillustrated in FIGURE 4. These rings are provided with sufficient heightto produce sufficient curving of both the rubber disc 43 and theabrasive disc 46 is produce proper topping even though the cup 47 ofFIGURE 4 `has a smaller diameter. The use of the removable rings 98provides machine iiexibility without requiring a series of differentwooden chucks 34 for different size cups 47.

Because the topping operation is performed by an abrasive disc which isshaped automatically to produce a smooth curved rim on the cup andbecause the cup is accurately positioned without requiring operatorskill the cost of topping is substantially lessened in two ways-firstnon-skilled labor can be used to operate the machine and second, higheroperating rates are possible.

Although a preferred embodiment of this invention is illustrated, it isto be understood that various modications and rearrangements of partsmay be resorted to without departing from the scope of the invention asdefined in the following claims.

` What is claimed is:

1. A topping machine for hollowware having a circular rim lying along aplane comprising a chum adapted to support the hollowware with the rimthereof exposed, an abrasive disc having a surface generally normal tothe axis of said rim, means connected to said disc operable toprogressively deform said disc while said disse engages said rim to ashape having portions of said surface extendd ing more nearly alignedwith the axis of said rim, and means connected to produce relativerotation between said 'lise and said rim, the progressive deformation ofsaid disc causing said disc to progressively shape said rim.

2. A topping machine for hollowware having a circular rim comprising achum to support the hollowware with the rim thereof exposed, an abrasivedisc having a surface generally normal to the axis of said rim, powermeans connected to said disc operable to progressively deform said discwhile said disc engages said rim to a shape symmetrical about said axishaving portions of said surface extending more nearly aliUned with 'theaxis of said rim and means connected to produce relative rotationbetween said disc and said rim, the progressive deformation of said disccausing said disc to progressively shape said rim.

3. A topping machine for ceramic hollowware having a circular rimcomprising a chum to support the hollowware with the rim thereofexposed, an abrasive disc element having a surface adapted to engage andsmooth said rim, said disc being formed of a mass of loose deformablefibers supporting space dabrasive particles, power means connected tosaid element operable to progressively deform said element while itengages said rim between two positions so that the element progressivelyrounds the surface of said rim, and means connected to produce relativemovement between said element and said rim.

4. A topping machine for hollowware having a rimcomprising a churn forsupporting piece of hollowware, a deformable member having an abrasivesurface, and power means operable while said surface engages to producerelative movement between said abrasive surface and the rim of a pieceof hollowware on said chum while progressively deforming said membercausing said surface to extend around said rim thereby progressivelyshaping said rim and producing a smooth rounded surface on said rim.

5. A topping machine for hollowware having a rim comprising a deformablemember having an abrasive surface, a chum for supporting a piece ofhollowware movable toward and away from said abrasive surface, and powermeans operable in response to chum movement to produce relativemovementbetween said abrasive surface and the rim of a piece ofhollowware on said chum while progressively deforming said membercausing said surface to progressively extend around said rim therebyproducing a smooth rounded surface on said rim.

6. A topping machine for hollowware having a rim comprising a deformablemember having an abrasive surface, a chum for supporting a piece ofhollowware movable toward and away from said abrasive surface, and powermeans operable in response to chum movement to produce relative movementbetween said abrasive surface and the rim of a piece of hollowware onsaid chum while progressively deforming said member causing said surfaceto progressively extend around said rim thereby producing a smoothrounded surface on said rim, said deformable member being formed of aloose mass of fibers supporting spaced abrasive particles.

7. A topping machine for hollowware having a rim symmetrical about anaxis comprising a chum adapted to` support a piece of hollowware withthe rim thereof exposed, a disc having an abrasive surface, supportmeans for said disc positioning said surface with a portion thereofsymmetrical about the axis of a piece of hollowware on said chum, powermeans operable to produce relative rotation between said disc and saidpiece of hollowware about said axis while said portion of said surfaceis in contact with the rim of said piece of hollowware, and meansoperable to progressively deform said portion of said surface betweenfirst and second positions while said portion engages said rim of saidpiece of hollowware, said portion of said surface extending generallynormal to said axis when in one of said positions and extending I morenearly parallel to said axis when in the other of said positions.

8. A topping machine for hollowware having a planar rim symmetricalabout an axis comprising a disc having an abrasive surface, a chumadapted to support a piece of hollowware with the rim thereof exposedand movable toward and away from said surface, support means for saiddisc positioning said surface with a portion thereof symmetrical about apiece of hollowware on said chum, power means operable to producerelative rotation between said disc and said piece of hollowware aboutsaid axis while said portion of said surface is in contact with the rimof said piece of hollowware, and power means operable in response tochum movement to progressively deform said portion of said surfacebetween rst and second positions while said portion engages said rim ofsaid piece of hollowware, said portion of said surface extendinggenerally normal to said axis when in one of said positions andextending more nearly parallel to said axis when in the other of saidpositions.

9. A topping machine comprising a chuck journaled for rotation about anaxis, a chum, a deformable backing member rotatable with said chuck andaxially supported along a circular Zone spaced from and co-axial withsaid axis, a deformable disc of abrasive supported for rotation withsaid backing member, and means carried by said chuck operable to axiallymove portions of said disc and backing member relative to said circularzone progressively deforming said disc while maintaining portions ofsaid disc symmetrical with respect to said axis.

10. A topping machine comprising a chum movable along an axis, arotatable chuck journaled for rotation about said axis, a foam rubberbacking member rotatable with said chuck and axially supported along acircular zone spaced from and co-axial with said axis, a deformable discof abrasive supported for rotation with said backing member, power meansoperable to axially move portions of said disc and backing memberrelative to said zone progressively deforming said disc whilemaintaining portions of said disc symmetrical with respect to saidaxis,l

and control means for said power means operated by axial movement ofsaid chum.

11. A topping machine comprising a chum movable along an axis, arotatable chuck journaled for rotation about said axis, a foam rubberbacking member rotatable with said chuck and axially supported along acircular zone spaced from and -co-axial with said axis, a deformabledisc of abrasive supported for rotation with said backing member, powermeans operable to axially move portions of said disc and backing memberrelative to said zone progressively deforming said disc whilemaintaining portions of said disc symmetrical with respect to said axis,and control means for said power means operated by axial movement ofsaid chum, said chuck having a central portion radially locating saidbacking member and limiting the extent of movement in one directionproduced by said power means.

12. A topping machine comprising a churn movable along an axis, a chuckrotatable about said axis, an abrasive disc mounted for rotation withsaid chuck and axially supported along a support zone, a power drivenassembly connected to a portion of said disc spaced from said supportzone and axially movable to move said portion axially relative to saidsupport zone, and resilient means operable to urge said churn in adirection away from said disc with a force which remains substantiallyconstant during the operation of said power driven assembly.

13. A topping machine comprising a chum movable along an axis, a chuckrotatable about said axis, an abrasive disc mounted for rotation withsaid chuck and axially supported along a circular zone radially spacedfrom said axis, a power driven assembly connected to a central portionof said disc inwardly spaced from said zone and axially movable to movesaid central portion axially relative to said zone, resilient meansconnected between -said assembly and chum operable to urge said chum ina direction away from said disc with a force which remains substantiallyconstant during the operation of said power driven assembly, and controlmeans operating said power driven assembly in response to axial movementof said chum.

14. A topping machine comprising a base, a chuck Vrotatable on said baseabout an axis, said chuck including an annular surface spaced from saidaxis co-axial therewith and a cylindrical surface inwardly spaced fromsaid annular surface and co-axial therewith, a backing disc of elastomermaterial formed with a central opening guided along said cylindricalsurface and a portion engaging said annular surface, a deformable discof abrasive engaging the surface of said backing disc remote from saidchuck, actuating means operatively connected to said abrasive discinwardly from said annular surface operable to move axially the centralportion of said discs relative to said annular surface, and a chumadapted to support a piece of hollowware co-axial with said axis andmovable along said axis.

1S. A topping machine comprising a base, a chuck rotatable on said baseabout an axis, said chuck including an annular surface spaced from saidaxis co-axial therewith and a cylindrical surface inwardly spaced fromsaid annular surface and co-axial therewith, a backing disc of elastomermaterial formed with a central opening guided along said cylindricalsurface and a portion engaging said annular surface, a deformable discof abrasive engaging the surface of said backing disc remote from saidchuck, actuating means operatively connected to said abrasive discinwardly from said annular surface operable to move axially the centralportion of said discs relative to said annular surface, a chum adaptedto support a piece of hollowware co-axial with said axis and movablealong said axis, control means for said actuating means operable inresponse to axial movement of said chum, springs operatively conectedbetween said chum and actuating means urging said chum away from saiddiscs, and a `stop limiting movement of said chum in a direction towardsaid discs.

16. A topping machine comprising a base, a. chuck rotatable on said baseabout an axis, said chuck including an annular surface spaced from saidaxis co-axial therewith and a cylindrical surface inwardly spaced fromsaid annular surface, a backing disc of rubber-like material formed withan opening guided along said cylindrical surface and a portion engagingsaid annular surface, a deformable abrasive disc engaging the surface ofsaid backing disc remote from said chuck, said abrasive disc beingformed of an open mass of lfibers supporting spaced hard particles,actuating means connected operatively to said abrasive disc inwardlyfrom said annular surface operable to axially move the central portionof said discs relative to said annular surface, a chum adapted tosupport a piece of hollowware co-axial with said axis and movable alongsaid axis, control means for said actuating means operable in responseto axial movement of said chum, springs operatively connected betweensaid chum and actuating means urging said chum away from said discs, anda stop limiting movement of said churn in a direction toward said discs.

References Cited UNITED STATES PATENTS 1,607,292 11/1926 Miller 51-227 X1,656,182 l/l928 Enna 51-373 2,334,572 11/1943 Melton 51-400 X 3,050,9098/1962 Rawstron 51-124 HAROLD D. WHITEHEAD, Primary Examiner,

1. A TOPPING MACHINE FOR HOLLOWWARE HAVING A CIRCULAR RIM LYING ALONG APLANE COMPRISING A CHUM ADAPTED TO SUPPORT THE HOLLOWWARE WITH THE RIMTHEREOF EXPOSED, AN ABRASIVE DISC HAVING A SURFACE GENERALLY NORMAL TOTHE AXIS OF SAID RIM, MEANS CONNECTED TO SAID DISC OPERABLE TOPROGRESSIVELY DEFORM SAID DISC WHILE SAID DISC ENGAGES SAID RIM TO ASHAPE HAVING PORTIONS OF SAID SURFACE EXTENDING MORE NEARLY ALIGNED WITHTHE AXIS OF SAID RIM, AND MEANS CONNECTED TO PRODUCE RELATIVE ROTATIONBETWEEN SAID DISC AND SAID RIM, THE PROGRESSIVE DEFORMATION OF SAID DISCCAUSING SAID DISC TO PROGRESSIVELY SHAPE SAID RIM.